QmakeProject parsing: Move code from gui thread to parser threads

Change-Id: I05c1ec01a2c1ae4017ad2d09b07aa87854e3f118
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>
~QmakeProFileNode: Simplify code

Change-Id: I6d56b8637b4194b57c4c0df033d0bc7919e24aeb
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>
QmakeProject: Make initial parse use the async parsing

Task-number: QTCREATORBUG-12123
Change-Id: I79dcd684fe826108189db521c392c0f1d7632f88
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>